Method of preserving fruits and vegetables fresh.



UNITED STATES PATENT OFFICE.

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Io Drawing.

To all whom it may concern:

Be it known that I, HELEN O. M.'.FB:ANK8, a subject of the King of Great Britain residing at No. lAlice Court, Brooklyn, bor ough of Queens, State of New York, have invented certain new and useful Improvements in Methods of Preserving Fruits and Vegetables Fresh, fully described and represented in the'following specification.

The object of this invention is to treat fruits, vegetables, and such perishable articles with a germ destro ing or inhibiting gas, as carbon dioxid (C in such a practical andeconomical manner, that at a rela tively small expense, the articles may be preserved from decay indefinitely, and retain their or' 'nal appearance and flavor; without whi their food value would be materiall diminished.

' ere it is required to keep the articles fresh for only a relatively short time, as a month'or two, and at a more or less even temperature and humidity, a charge of the CO gas is applied once under a considerable pressure to the articles, and the pressure repeated after a gradual exhaustion of the No heat is used in my method of preserving, as the very object of my methods is to preserve the natural qualities of the articles unchanged,

When it is required to preserve the fruit for a long time, as on a voyage or journey in which it will be carried through various latitudes, and thus exposed to differences of temperature and humidity, the first charge first charge.

of CO gas is extracted from the articles by a parti vacuum before the second charge of CO is applied; and other char es of CO and of nitrogen are applied to t e articles at carefully graduated pressures, which charges completely remove any tendency to decay or fermentation under any conditions.

Durin the treatment, the articles are packed in suitable separate permanently charged containers of any suitable size and material. Each container has an independent open communication with the atmosphere, and any required number of such containers is inclosed in a tight chamber of suitable size and strength to receive them, andcto sustain the pressure at which the gas is applied. Each container provided w1th means to hermetically seal it in a partial Specification of Letters I'atent;

vacuum at the close of the treatment, and means is prov ded within the chamber to seal all the containers before they are brought out into the air.

I am aware that it has been roposed to use CO as a preserving agent, ut its successful or effective use requires that the pressure of its application should be great, but applied in such a manner as not to crush the fruit; and its withdrawaleffected in such a manner as not to expand and rupture the fruit, and the mere suggestion of its use is of no real value.

To be effective, the resent invention includes various specific steps, practised in a prescribed manner, which longexperiment lowest efiicient pressure, and the safe modeof applying it.

By such means applied in a certain manner, is necessary to protect such articles effectively from change, and that such pressure may be safely applied by observing the following rules, which were also ascertained by repeated experiments The term process is used herein to include all the successive treatments, specified in any claim, by subjecting the article to the pressure of a gas or to the exhaustionof air and gases from its tissues. The term treat- .ment will be understood as applicable to any one step in the process.

To meet commercial requirements, the tightly closed chamber receiving the gas under a pressure of lbs. pressure per square inch is made of suitable size to admit a large number of containers, as glass jars or tin cans, and to support them in proper connection with sealing mechanism, which I have determined that a a pressure of 60 lbs. per square inch for CO Patented July 3, 1917.

Application filed April 24, 1917. Serial misuse,

Q 1,aaa

can be actuated from the exterior of the chamber while a vacuum is maintained therein.

I have described one method of treating the articles, and another method which is a specific form of the first method involving additional treatments, which will preserve the fruit or vegetable articles indefinitely.

The method for a partial preservation of the fruit I call method A, and practice it as follows:

The containers permanently charged with the 'fruit or vegetablesto be treated, being thus arranged in the chamber, the CO gas is introduced and the pressure gradually increased, for a period of ten to twenty minutes, to a pressure of 60 to 70 lbs. per square inch, which is maintained for twenty minutes. This pressure is very gradually reduced to atmospheric pressure, allowing twenty to thirty minutes for the CO gas in the articles to escape.

This step removes from the chamber much of the air first contained therein; but a partial vacumm (one-half of the atmospheric pressure or 16 inches of mercury) is necessary to remove the air more completely, and I therefore generate such vacuum within the chamber very gradually for a space of ten to twenty minutes, thus avoiding any rupture of the skin of delicate fruit, as ripe peaches. I then again supply CO, to this exhausted chamber, carrying the pressure very gradually for twenty minutes to 60 lbs. per square inch, as before.

I subject the articles to this gas for a period of one hour after it has attained that pressure, and then very, very slowly discharge this gas, with any mingled air, and exhaust the chamber to ayacuum of at least sixteen mercury inches.

It is exceedingly needful that this exhaustion of the chamber be*efi'ected steadily at a uniform rate, as any pulsations in the atmosphere of the chamber, whicha vacuum pump may produce, is very detrimental to the fruit from which the gas and air are being extracted during such exhaustion. Sudden'pressure may crush the fruit, but the danger from pressure is not half so serious as that from sudden or uneven or too quick evacuation.

When the final vacuum has been gradually attained, the containers are sealed in such vacuum within the chamber in a rarified at mosphere of CO, while protected from any exposure to the outer air; and the two pressures of the CO will be found sufficient to preserve such articles for one or two months as the treatments, by the gas and exhausti'fins, operate to displace nearly all the air or gases in the tissues of the articles, and replace them with the preservative gases. Further treatmentsmay be applied when the articles are to bekept for a long period or indefinitely, and in such case I call the process method B.

In method B, which is a specific form of the invention, I charge a third time with the CO, at 60 pounds per square inch, and then with nitrogen gas at 20 pounds per square inch, such method embracing the following ste s: 'rst, the treatment with CO, gas maintained for not less than twenty minutes;

Second, the production of a' vacuum of about 16 inches of mercury;

Third, the treatment with CO, continued for about one hour;

Fourth, the production of a vacuum of at least 16 inches of mercury;

Fifth, a third treatment with ()0 at (30 pounds pressure continued for several hours;

Sixth, the production of a partial vacuum to exhaust such nitrogen gas from the articles; and,

Seventh, the treatment of the articles with nitrogen gas at 20 lbs. for a period of three hours, and this gas is then very slowly drawn oil and the chamber exhausted to 16 inches of mercury, and the containers sealed in the, remaining nitrogen atmosphere. This treatment insures the fruit from alteration or decay under any and all conditions.

This method B subjects the articles to gas pressure four times; three times to CO at 60 lbs. pressure, and once to nitrogen gas at 20 lbs. pressure; but substantially the same efiicient result can be secured in a third method by using nitrogen gas in both the last two treatments, with a complete evacuation of the chamber intermediate to the two. This method I call method C.

It will be observed that in the treatments for preserving the article a moderate length of time, the two gas pressures are exerted for periods of 20 minutes and 1 hour, respectively, but that for preserving the article indefinitely two further treatments. are

applied and the pressure in each maintained for 3 hours. Such treatment under pressure for a total of 6 hours obviously produces a far greater eifectupon the article than the two treatments of 1 hour and 20 minutes a plied for preserving the article for use with- 1n a month.

The sealing of the containers while inclosed in the chamber is effected by providing the lid or closure of each container with an inlet having means to tightly seal it; and such means may afiord an opportunity to strengthen the said seal by solder or otherwise, after the containers are removed from the chamber.

Having thus set forth the nature of the invention what is claimed herein is:

1. In the preparation of fruits and vege pressure between and 70 pounds per square inch for twenty minutes to one hour respectively, and after each application of the CO subjecting the fruits'or vegetables 5 to a vacuum of 16 inches of mercury and finally sealing them in a vacuum. 2. The process of preserving fruits and vegetables, which consists in inclosing in a tight chamber a container charged ermanently with the fruit, the container aving an open communication with the atmosphere of the chamber and means adapted for hermetically sealing the same, forcing CO into the chamber to a pressure between 60 and 70 pounds per square inch, maintaining such pressure for at east ten minutes, then very slowly dischar 'ng the CO and the air mixed therewit ,to atmospheric pressure, then exhausting the chamber very gradually, then very graduall for about 15 minutes renewing the O to a pressure between 60 and 70 pounds per square inch and maintaining the pressure of such (JO upon the fruit for at least one hour, then very slowly discharging the gas and mingled air from-the chamber, and excluding the air therefrom, and sealing the container within the chamber before removal therefrom.

3. In the treatment of fruits and vegetables in a plurality of containers simultaneously within a single chamber, the containers being permanently charged with the articles to be treated and constructed to be sealed, and having independent open communication with the atmosphere in the chamber, that process which consists in. subjectin the entire contents ofthe chamber to C 2 at a slowly generated pressure be tween 60 and 70 pounds per square inch, maintaining such ressure not less than ten minutes, slowly discharging such gas and air mingled therewith, very slowly exhausting the chamber'to a vacuum of 16 inches of mercury, then supplying CO to this exhausted chamber, carrying the pressure very gradually to at least 60 pounds per square inch, maintaining such pressure for at least one hour, slowly discharging the gas under pressure in the chamber and again exhausting the chamber to a vacuum of at least 16 inches, and finally closing the containers within the said chamber before removal therefrom, to protect their contentsfrom the atmosphere.

4. The process of. preserving fruits and vegetables, which consists in subjecting the fruits and vegetables in a tight chamber,

first, to an atmosphere of CO, under'a'pressure of about 60 pounds per square inch and afterward discharging such pressure and subjecting the fruit to nitrogen gas at a pressure of not less than 20 pounds.

5. The process of preserving fruits and vegetables, which consists in mclosing the container, permanently charged with the. fruit in a tight chamber, forcing CO 'intO the chamber to a pressure of-60 to 70 pounds and maintaining such ressure for three hours, dischar 'ng the C 2 and mingled air from the chem er and exhausting the chamber to at least one-half the atmospheric pressure, then forcing nitrogen at not less than 20 pounds pressure per square inch into the chamber and maintaining such pressure of nitrogen s for "three hours, then discharging the mtrogen gas and partially exhausting the chamber, and sealing the receptacle in such partial vacuum before removal from the chamber.

6. The process of preserving fruits and vegetables, which consists in inclosing in a tight chamber a container permanently charged with the fruit, the container having an o communication with the atmosphere of tli s chamber and means adapted for hermetically sealing the same, forcing 00 into the chamber to a pressure between 60 and 70 pounds per square inch, maintaining such pressure for ten or twenty minutes, then very slowly discharging CO and the air mixed therewith to atmospheric pressure, then exhausting the chamber very gradually, to 16 inches mercury, then very gradually during a eriod of fifteen minutes renewing the O to a pressure between 60 and 70 pounds per square inch and maintaining the pressure of such CO, upon the fruit for one hour, then for a period, of fifteen minutes slowly discharging the gas and, mingled air toatmospheric pressure, the reduction in pressure being1 steady and uniform to prevent injury to t e tissues of the fruit, then renewing the CO at 'a pressure of 60 to 70 ounds per square inch and maintainin suc pressureto o erate upon the fruit t ree hours, then disc arging the gas and mingled air, and forcing nitrogen gas into the chamber to a pressure of 20 pounds per s uare inch and maintaining such pressure or three hours, then removing the nitro gas and creating a vacuum of sixteen in es of mercury and sealing the container in such vacuum.

In testimony whereof I have hereunto set my hand.

HELEN OEOILIA MARGARET FBAHKB. 

